<?php

/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Auth
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Auth.php 24593 2012-01-05 20:35:02Z matthew $
 */
/**
 *
 * @category Zend
 * @package Zend_Auth
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
class Zend_Auth {

    /**
     * Singleton instance
     * @var Zend_Auth
     */
    protected static $_instance = null;

    /**
     * Persistent storage handler
     * @var Zend_Auth_Storage_Interface
     */
    protected $_storage = null;

    /**
     * Singleton pattern implementation makes "new" unavailable
     * @return void
     */
    protected function __construct () {}

    /**
     * Singleton pattern implementation makes "clone" unavailable
     * @return void
     */
    protected function __clone () {}

    /**
     * Returns an instance of Zend_Auth
     * Singleton pattern implementation
     * @return Zend_Auth Provides a fluent interface
     */
    public static function getInstance () {
        if (null === self::$_instance) {
            self::$_instance = new self ();
        }
        return self::$_instance;
    }

    /**
     * Returns the persistent storage handler
     * Session storage is used by default unless a different storage adapter has been set.
     * @return Zend_Auth_Storage_Interface
     */
    public function getStorage () {
        if (null === $this -> _storage) {
            /**
             *
             * @see Zend_Auth_Storage_Session
             */
            require_once 'Zend/Auth/Storage/Session.php';
            $this -> setStorage (new Zend_Auth_Storage_Session ());
        }
        return $this -> _storage;
    }

    /**
     * Sets the persistent storage handler
     * @param Zend_Auth_Storage_Interface $storage
     * @return Zend_Auth Provides a fluent interface
     */
    public function setStorage (Zend_Auth_Storage_Interface $storage) {
        $this -> _storage = $storage;
        return $this;
    }

    /**
     * Authenticates against the supplied adapter
     * @param Zend_Auth_Adapter_Interface $adapter
     * @return Zend_Auth_Result
     */
    public function authenticate (Zend_Auth_Adapter_Interface $adapter) {
        $result = $adapter -> authenticate ();
        /**
         * ZF-7546 - prevent multiple succesive calls from storing inconsistent results
         * Ensure storage has clean state
         */
        if ($this -> hasIdentity ()) {
            $this -> clearIdentity ();
        }
        if ($result -> isValid ()) {
            $this -> getStorage () -> write ($result -> getIdentity ());
        }
        return $result;
    }

    /**
     * Returns true if and only if an identity is available from storage
     * @return boolean
     */
    public function hasIdentity () {
        return  ! $this -> getStorage () -> isEmpty ();
    }

    /**
     * Returns the identity from storage or null if no identity is available
     * @return mixed null
     */
    public function getIdentity () {
        $storage = $this -> getStorage ();
        if ($storage -> isEmpty ()) {
            return null;
        }
        return $storage -> read ();
    }

    /**
     * Clears the identity from persistent storage
     * @return void
     */
    public function clearIdentity () {
        $this -> getStorage () -> clear ();
    }

}
